The sartorius muscle is the main flexor of the thigh. This muscle is the longest muscle in the human body. It is both a flexor, an abductor and a rotator of the thigh at the hip joint, working in conjunction with other major muscles of the hip.
The sartorius muscle is located at the anterior superior iliac spine on the lateral edge of the hip bone. From there, it descends across the hip joint and the thigh. The sartorius muscle turns laterally at the knee to descend to the medial side of the tibia. The word "sartorius" means "tailor" in Latin, so the sartorius muscle is sometimes called the tailor's muscle.